(NaturalNews) Researchers have discovered that a clay made from volcanic ash in France has powerful antibiotic properties and is capable of killing even antibiotic-resistant superbugs such as methicillin-resistant Staphylococcus aureus (MRSA).

"It's fascinating," said researcher Shelley Haydel, a microbiologist at Arizona State University. "Here we are bridging geology, microbiology, cell biology. A year ago, I'd look at the clay and say, 'Well, that's dirt.'"

MRSA is an antibiotic-resistant variety of the common bacteria that causes staph infections. This makes it more likely to develop potentially fatal complications, as it can proceed untreated for longer and spreads rapidly in institutional settings such as hospitals, prisons and schools.

Researchers added the volcanic clay, called agricur, to cell colonies of MRSA, and found that 99 percent of colonies were eliminated within 24 hours. In the same time period, colonies not treated with the clay grew by 45 percent. The clay exhibited similar antibiotic effects against salmonella, E. coli and buruli.

Buruli is a flesh-eating relative of leprosy that causes disfigurement of children. Due to its prevalence in Africa, the World Health Organization has classified it as "an emerging public health threat."

The researchers do not yet know what about the clay is responsible for its antibiotic properties. While clay has a history as a folk remedy for nausea and a spa treatment, the former use has not been seriously studied and the latter is due to clay's ability to hold heat and draw out toxins.

"We have multiple working hypotheses," to explain the properties of antibacterial clay, researcher Lynda Williams said. "Our primary hypothesis is that the clay minerals transfer elements, not yet identified, to the bacteria that impede their metabolic function. It is entirely possible that it is not one single element that is toxic to the bacteria, but a combination of elements and chemical conditions that attack the bacteria from different angles so as to overwhelm their defense systems."

While unlikely, it is also possible that the clay kills bacteria through physical rather than chemical processes, which would make it incredibly difficult for the bacteria to develop resistance to it.